THE NATURE OF THE SERUM CONSTITUENT AFFECTING PLAIN MUSCLE

¹ The Department of Physiology, Edinburgh University

The constituent of serum which produces increased contraction of plain muscle is not protein, is dialysable, not volatile with steam, not destroyed by boiling or by drying, but is destroyed by ashing. It is insoluble in ether, acetone and chloroform, but is soluble in boiling alcohol, and with difficulty in cold alcohol. It is not destroyed by 1 per cent alkali in the cold or at 100° C., nor by 1 per cent sulphuric acid in the cold ; but sulphuric acid at 100° C, rapidly destroys it. It may be removed from solution by certain adsorbents. It exists in the human red cells as well as in the serum.

This research was aided by a grant from the Earl of Moray Fund of the University of Edinburgh.